Modern fabric comprises synthetic materials (e.g., Dacron), natural fibers (e.g., cotton), as well as blends thereof, however many skilled in the laundry art consider fabric to have two embodiments: white fabric and colored fabric. The consumer has long recognized the need to delineate between colored and white clothing. It was the common "wash-day" observation that many colored fabrics had a propensity to "bleed" into the laundry liquor and deposit onto other fabrics that led to the practice of sorting clothes into white fabric and colored fabric. In addition, because of problems with color fading, dyed fabric can not be laundered at the hotter water temperatures typical for whites. Once sorting became a standard practice within the laundry art, separate processes and materials evolved for cleaning these separated white and dyed fabric. The introduction of hypochlorite bleach into the laundry process, because it is not compatible with many fabric dyes, solidified the establishment of white and dyed material as the two major laundry categories.
Hypochlorites are among the most common non-surfactants used to enhance the appearance of white, non-dyed fabrics. These bleaches chemically destroy the colored stains present on white fabric and it is generally regarded that for highly conjugated, fixed stains, the first treatment with bleaching agents oxidizes the stain-producing molecules to a non-colored or less colored species that is subsequently removed in the rinse cycle. For more difficult stains, further treatment with bleach is necessary, although the over usage of bleach can damage even white fabric. The desire to enhance fabric whiteness appearance has led to the development of many adjunct laundry ingredients. One such material is optical brighteners added to reduce the yellow cast that develops on white fabrics after successive washings.
Optical brighteners have no other purpose than to enhance the appearance of fabric. Indeed, many synthetic fabrics have optical brighteners built into the fibers or fixed onto the synthetic fabric during manufacture. These additional brightening agents help to compensate in part for the yellow cast that develops when non-colored fabrics are washed in water containing heavy metal ions. However despite the use of bleaches, the incorporation of brighteners into the fabric, and other whiteness enhancing materials, some level of dinginess still persists on many white fabrics after several washings.
For colored fabrics a different set of fabric enhancement principles exists. Although dyed and white fabrics often comprise the same natural or synthetic materials, many of the dyes used to color fabrics are susceptible to the harsh bleaching conditions used to "whiten" non-dyed fabrics. The desire to remove stains from dyed fabric has provided further impetus for the development of separate non-damaging bleaching materials for colored fabrics. However, safe stain removal is only one issue that is connected to colored fabrics. Colored materials must be guarded against fading, a condition where the original color is lost due to one or more conditions. The problems of fading, change in color intensity, or color hue are even more perceptible than the "yellowing" of whites. In fact, consumers are well aware that garments comprising different materials, but having the same color, may fade at different rates in the laundry process. Therefor, non-soiled garments loose their "new" appearance simply from washing alone, and agents are needed to enhance their appearance, that is to make the fabric appear more "new-like".
Surprisingly, the materials disclosed in the present invention provide for increased color protection and appearance enhancement for both white and colored fabrics. The dinginess often described as a yellow cast, brownish discoloration, or graying that develops on white fabrics is reduced while the color fading and changing of color-hue of dyed fabrics are marginalized.
Treatment in an automatic clothes dryer has been shown to be an effective means for imparting desirable tactile properties to fabrics. For example, it is becoming common to soften fabrics in an automatic clothes dryer rather than during the rinse cycle of a laundering operation. (See U.S. Pat. No. 3,442,692, Gaiser, issued May 6, 1969, incorporated herein by reference.)
Prior to the present invention, dryer-added color protectants could suffer from uneven dispersal onto fabric and the result was a "blotchy" or "mottled" appearance. However, the modified polyamines of the present invention when formulated with a suitable carrier (e.g., stearic acid) provide an evenly applied material that serves as a color fidelity agent. The compounds useful in the compositions of the present invention are in general highly effective against the heavy metal ions responsible for color fidelity problems (e.g., copper) and against ions (e.g., manganese) that effect the dinginess of white fabrics.
Fabric "softness" is an expression well-defined in the art and is usually understood to be that quality of the treated fabric whereby its handle or texture is smooth pliable and fluffy to the touch. Various chemical compounds have long been known to possess the ability to soften fabrics when applied to them during a laundering operation.
Fabric softness also connotes the absence of static "cling" in the fabrics, and the commonly used cationic fabric softeners provide both softening and anti static benefits when applied to fabrics. Indeed, with fabrics such as nylon and polyester, the user is more able to perceive and appreciate an anti static benefit than a true softening benefit.
These dryer added fabric softener compositions typically comprise one or more cationic and/or nonionic softening and/or anti-static agents in combination with one or more conditioning agents. Typically these compositions are adapted for use by affixing the composition to an article of manufacture which serves as the means for dispensing said fabric conditioning compositions.
In addition to the fabric appearance benefits, it has now beer surprisingly found that the polyamines of the present invention when taken together with a suitable carboxylic acid carrier provide not only the surprising above-mentioned dryer-added fabric enhancement benefits but anti-static and fabric softening benefits as well. Normally anti-static and fabric softening benefits were only achievable by a combination of two or more ingredients. This combination of fabric care benefits is also deliverable without the need for other adjunct ingredients typically found in other fabric treatments. However, the polyamines of the present invention can be formulated just as well with existing fabric anti-static and conditioning compositions to provide color enhancement benefits.
U.S. Pat. Nos. 4,764,289, Trinh, issued Aug. 16, 1988 and 4,818,569, Trinh et al., issued Apr. 4, 1989 include anionic soil release polymers together with cationic and nonionic softening/anti-static agents for added fabric treatment benefits. These disclosures provide an example of the increasing benefits deliverable via the clothes dryer as more materials are formulated into the softening/anti-static compositions.
The compounds of the present invention which serve to provide fabric enhancement benefits as well as fabric anti-static and conditioning benefits are polyvinyl amines and polyalkyleneimines (PEI's) or polyalkyleneamines (PEA's). These amines can be modified by poly(alkyleneoxy) substitution of some or all polymer backbone nitrogens. These modifying polyalkoxy moieties replace the hydrogen atoms bonded to the polyamine backbone nitrogens.